X76HVD-4气相输入模块

The Model X76HVD-4 Module is part of the X76LVC and X76LVCS Leak Detection Systems. It measures the vapor concentration in vadose wells, groundwater wells or secondary contained vessels. The microprocessor based input module measures the sensor resistance, which is directly proportional to the vapor concentration and displays the linearized values in parts per million （ppm） via the front panel mounted 4?digit LED display. The X76HVD-4-2.5 Module is calibrated for a range of 0 to 2,500 ppm for products such as waste oil, diesel, JP-5, etc. The X76HVD-4-20 is used over the range of 0 to 20,000 ppm to measure gasoline, methanol, benzene, toluene, etc. Each module features an adjustable setpoint normally set for 25% of the lower explosive level （LEL） of the specific product monitored. The setpoint is adjusted to the desired ppm readout on the LED display by a front panel mounted potentiometer. Should the vapor concentration exceed the setpoint, a red flashing LED provides visual alarm, an audible alarm is actuated and a transistor switch output operates. The system抯 common acknowledge push button silences the audible alarm. The LED remains flashing until the vapor concentration returns below the setpoint level.

The module features a front panel mounted amber LED indicator for sensor failure and a two-color LED, green for power on, turning red to show faulty wiring, e.g. short, open or incorrect polarity. Optionally, a contact or conductivity type level switch connected to the module provides indication （red LED） that the sensor is submerged.